- If a split is a subset of a partition, what is the meaning of SplitDataProperties#splitsPartitionedBy? The wording makes me thing that a split is divided into partitions, meaning that a partition would be a subset of a split.

- At which point can I retrieve and adjust a SplitDataProperties instance, if possible at all?

- If I wanted a coarser parallelization where each slot gets all the data for the same host, would I have to manually create the sub-groups based on timestamp?